Harvest control unit for an ice-making machine

ABSTRACT

A harvest control unit for an ice-marking machine characterized by an actuatable switch adapted to provide an output signal for electrically initiating a harvest of ice from the machine, and switch-actuating means responsive to variations in the flow of water for actuating said switch including a receiver pan for receiving the variable flow of water, a manifold chamber connected with the receiver pan having a metering orifice defined within the chamber for discharging water from the manifold at a substantially fixed rate, a holding tank for confining a relatively warm body of water supported in spaced relation with the manifold chamber and communicating therewith, and a buoyant mass supported by said body of water and connected with the switch means for actuating the switch in response to variations in the level of the body of water.

United States Patent Creager HARVEST CONTROL UNIT FOR AN ICE-MAKING MACHINE [75] Inventor: Olen R. Creager, Fresno, Calif.

[73] Assignee: InternationalRefrigeration Engineers [22] Filed: Oct. 11, 1973 [21] Appl. No.: 405,295

[52] US. Cl. 62/138; 62/352; l37/101.25

[51] Int. Cl F25c 1/06; F25c 1/12 [58] Field of Search 62/352, 138; l37/l0l.25, 137/10l.27

[56] References Cited UNITED STATES PATENTS 3,068,660 12/1962 Council et al. 62/352 X Primary ExaminerWilliam E. Wayner Attorney, Agent, or FirmHuebner & Worrel [57] ABSTRACT A harvest control unit for an ice-marking machine characterized by an actuatable switch adapted to provide an output signal for electrically initiating a harvest of ice from the machine, and switch-actuating means responsive to variations in the flow of water for actuating said switch including a receiver pan for receiving the variable flow of water, a manifold chamber connected with the receiver pan having a metering orifice defined within the chamber for discharging water from the manifold at a substantially fixed rate, a holding tank for confining a relatively warm body of water supported in spaced relation with the manifold chamber and communicating therewith, and a buoyant mass supported by said body of water and connected with the switch means for actuating the switch in response to variations in the level of the body of water.

7 Claims, 3 Drawing Figures EVAPORATOR RR SECTION Z 64 6R 5/? CONDENSOR L COMPRESSOR R0 RESERVOIR V SECTION SECTION 38 HARVEST CONTROL UNIT FOR AN ICE-MAKING MACHINE BACKGROUND OF THE INVENTION The invention relates to a harvest control unit for an ice-making machine, and more particularly to a harvest control unit for controlling the harvest of ice in response to variations in the rate of flow of water through the ice-making machine;

Ice-making machines suited for automatically and cyclically producing ice pellets are well known andfrequently are found in various commercial establishments including hotels, restaurants, dairies and the like. U.S. Letters Pat. No. 3,068,660 which issued Dec. 18. 1962 and U.S. Letters Pat. No. 3,392,540 which issued July 16. 1968 disclose typical ice-making machines.

The prior art machines typified by the aforementioned patents include an evaporator section having a first tube through which water is circulated continuously, and an outer tube which constitutes a tempera.- ture control jacket. Through the temperature control jacket a gaseous refrigerant and a heated gas alternately are circulated for cyclically freezing water within the tube, to thus form an ice deposit along the wall thereof. and thereafter heating the tube for initiating an ice-harvesting operation.

In the ice-making machines of the type aforementioned, a stream of water is pumped through the machine at a rate of flow which substantially exceeds that at which ice is deposited on the inner surface of the inner tube. Hence, various attempts have been made to utilize the flow ofthe water pumped through the tube as a means for controlling the cylic rate of the machine. For example. attempts have been made to utilize pressures developed in the feed line to the evaporator section for initiating ice-harvesting operations. Another approach has been to detect flow rates through the feed line and to initiate ice-harvesting operations asthe flow therethrough is reduced to a predetermined level. Still another approach to achieving cyclic control has encompassed the concept of utilizing a control unit which responds to variations in the rate of discharge flow from the evaporator section, for initiating iceharvesting operations; as more fully described in the aforementioned U.S Letters Pat. No. 3,068,660.

The control unit suggested by the aforementioned patent for performing the desired function of responding to variations in the rate of discharge flow for initiating ice-harvesting operations includes a tank for receiving the discharge flow from the evaporator section, an

orifice of a predetermined diameter'provided in thetank for metering the flow of water from the tank, and a float switch including a buoyant mass deposited within the tank for initiating ice-harvesting operations, as the rate of the discharge flow from the evaporator sections diminishes to a predetermined level. One of the difficulties encountered in employing control units of this type results from the simple fact that the water being received within the tank often is at or near freezing temperatures and includes slush, particularlyjust prior to the point in the machine's operational cycle at which ice-harvesting should be initiated. As a consequence, the metering orifice tends to become clogged by the ice for thereby restricting the flow of water so that the rate at which the water is discharged from the tank is reduced. Consequently, initiation of iceharvesting operations is delayed. Of course. a delay in LII the harvest of ice from the machine results in problems which simply cannot be tolerated, for reasons readily apparent to those familiar with the operation of icemaking machines of the type aforementioned.

In an effort to avoid such consequences, attempts have been made to employ an auxiliary jet of relatively warm water for continuously clearing the metering port, as is also disclosed in the aforementioned U.S. Letters Pat. No. 3,068,660. While such attempts have met witha degree of success, the resulting complexity increases at a rate disproportionate to the rate at which dependability of the control unit is increased. Moreover, such tubes are subject to fouling by mineral deposits which render them inoperative.

It is therefore the general purpose of the instant invention to provide a simple, economic, and dependable control unit through which ice-harvesting operations are initiated in ice-making machines ofa type including an ice-making tube, means for delivering a continuous flow of water through the tube at a variable rate, as a collection of ice is formed along the wall of the tube, and a hot-gas circuit for effecting a release of the collection of ice to thus initiate ice-harvesting operations.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the instant invention to provide an improved harvest control unit for an icemaking machine.

It is another object to provide an economic, practical and dependable harvest control unit for initiating iceharvesting operations within ice-making machines of a type including an evaporator section through which a continuous flow of water at a variable rate is main- .tained.

It is another object to provide in an ice-making machinean improved harvest control unit capable of dependably sensing variations in the discharge rate of a flow of water from an evaporator section of ice-making machines, and to initiate ice-making operations in response to variations in the rate of flow.

It is another object to provide in a harvest control unit for an ice-making machine a sensing mechanism capable of sensing variations in the discharge rate of a continuous flow from an evaporator section, without experiencing icing.

It is another object to provide in combination with an ice-making machine having means for maintaining a variable flow of water through the machine, a harvest control unit including an actuatable switch means adapted to provide an output signal for electrically initiating harvesting of ice from the machine, and a switch actuating means responsive to variations in the flow of water for activating the switch means, and means for preventing an icing of the control unit.

These and other objects and advantages are achieved through the use ofa receiver pan for receiving the flow of water discharged from the evaporator section of an ice-making machine, a manifold chamber connected with the receiver pan including therein an ice-free metering orifice disposed in spaced relation with the receiving pan, a holding tank for confining a relatively warm body of water having a variable level supported in spaced relation with the manifold chamber and communicating therewith through a port disposed within the lower portion of the holding tank, and a float switch connected with the holding tank responsive to variations in the level of the body of water for actuating a switch to provide an electrical output signal for initiating ice-harvesting operations, as will become more readily apparent by reference to the following description and claims in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectioned schematic view of an ice-making machine including a control unit which e m bodies the principles of the instant invention.

FIG. 2 is a partially sectioned side elevation illustrating a manifold chamber embodied within the control unit shown in FIG. 1.

FIG. 3 is a fragmented end view of the manifold chamber shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now with more specificity to thedrawings wherein like reference characters designate like or corresponding parts throughout the several views, there is schematically depicted in FIG. 1 an ice-making machine, generally designated 10, having a harvest control unit, generally designated 12, through which cyclic operation control is imposed on the machine.

The machine is of a type more fully described in the aforementioned U.S. Letters Pat. No. 3,068,660, Therefore, a detailed description of the machine 10 is omitted in the interest of brevity. However, it is to be understood that the machine 10 includes an evaporator section 14 provided with an ice-making tube 16 concentrically related to an outer tube 18. The tube 18 defines about the tube 16 a void which serves as a temperature control jacket, not designated. As shown, the concentrically related tubes 16 and 18 are of a helical configuration, however, for reasons which should readily be apparent, the tubes may be of any other suitable configuration.

A pump 20 is connected with the ice-making tube 16 through a feed line 22 and continuously serves to supply a head of water to the evaporator section 14. It is important to note that at the discharge end of the icemaking tubes I6, there is provided a discharge orifice 24 through which water is discharged from the evaporator section 14. As a practical matter, the configuration of the tube 16, adjacent to the discharge orifice 24, is varied for causing the ice to crack as it is forced from the tube during ice-harvesting operations.

The temperature control jacket formed by the outer tube 18 communicates with a condensor-reservoir section, designated 26, through a suitable feeder line 28. A compressor section is connected, at its input side, with the outlet side of the temperature control jacket through a discharge line 32. The output side of the compressor section 30 is connected with a selector valve 34 through a pressure line 36, which, in turn, is connected to the condensor-reservoir section 26, through a feeder line 38, and to a by-pass line 40. The by-pass line terminates at a suitable T-fitting. not designated, provided in the feeder line 28.

It should therefore readily be apparent that the valve 34, when in a first position, serves to connect the compressor section 30 with the condensor-reservoir section 26 and, when in a second position, serves to connect the compressor section 30 with the feeder line 28, directly, whereby the condensonreservoir section 26 is by-passed. Consequently, it is to be understood that when the valve 34 is in its first position, a gaseous refrigerant is delivered from the condensor-reservoir section to the temperature control jacket, defined by the outer tube 18, and when the valve is in its second position heated gas derived from the compressor section 30 is delivered to the temperature control jacket, via the by-pass line 40.

It is to be understood that the pump 20 delivers a continuous stream of water through the evaporator section 14. Therefore, as refrigerant is introduced into the temperature control jacket, defined by the outer tube 18, a collection of ice adheres to the inner walls of the ice-making tube 16. As this collection of ice continues to thicken so that the flow rate, or quantity per unit of time, of the stream of water discharged from the discharge orifice 24 is substantially reduced. At a predetermined point in its cycle of operation the machine initiates an ice-harvesting operation. This is effected by switching the valve 34 to its second position whereupon heated gas is delivered to the temperature control jacket, defined by the outer tube 18, via the by-pass line 40 and the feeder line 28. The wall of the icemaking tube 16 is thus heated so that ice adhered thereto tends to release, whereupon back pressure established in the feeder line 22 serves to force the ice from the evaporator section 14.

As the ice is passed through the tube l6, in the vicinity of the discharge orifice 24, it is caused to change direction due to the configuration of the tube 16. As the ice is caused to change direction, a fracture thereof occurs so that the ice ultimately is discharged from the orifice 24 as cylindrical segments, or pellets. Another cycle of operation for the machine isinitiated simply by reversing the position of the valve 34 to its first position.

In practice, a spring-loaded solenoid 42 is provided for actuating the selector valve 34. Therefore, it is to be understood that the valve is maintained in its first position in response to the effects of the spring of the solenoid, while an electrical signal ,applied across the solenoid 42 causes the valve 34 to switch to its second position, all in a manner well understood by those familiar with solenoid-actuated valves. Accordingly. it should be apparent that ice-harvesting operations are initiated in response to an electrical signal applied to the solenoid 42.

The solenoid 42 is electrically connected to a float switch 44 provided within the control unit 12. A suit able signal conductor 46 serves quite satisfactorily for this purpose. The float switch 44, as a practical matter, includes a pivotally supported mercury switch, not shown, connected with a buoyant mass 48 through a suitable lever arm 50. Since float switches are well known, a detailed description of the switch 44 is omitted in the interest of brevity. However, it is to be understood that the switch includes means defining a shorting bar through which an electrical circuit is completed between the signal conductor 46 and a source of electrical potential not shown, response to a lowering of the mass 48. A raising of the mass 48 permits the switch to open for thus interrupting a circuit between the signal conductor 46 and the source of electrical potential, all in a manner well understood by those familiar with float switches and similar devices.

While the switch 44 is mounted in any suitable manner, the float switch 44, as illustrated, is supported on a vertical wall of a holding tank 52 through a suitable bracket 54 attached thereto. A wing-nut and stud assembly 58 are readily employable for coupling the float switch 44 with the bracket 54, preferably in a manner such that the float switch 44 can be adjusted vertically relative to the holding tank 52. In any event, the buoyant mass 48 is supported by a body of water of a variable level, designated 60, confined within the holding tank 52, and activation of the float switch 44 is dictated by the positions assumed by the lever arm 50, as the level of the body of water 60 is caused to vary.

in practice, water is supplied to and extracted from the holding tank 52 via a port 62, provided in the lowermost portion thereof, and tubular conduit 64 connected therewith and extended to communicate with a manifold housing 66. While not shown, it is to be understood that suitable fittings are provided for coupling the conduit 64 with the holding tank 52 and the mani fold housing.

The manifold housing 66 is mounted at one side of a receiver pan 68 and in coaxial alignment with an outlet orifice 70 provided in the lower portion of the receiver pan 68. The receiver pan 68 serves to confine a body of water, designated 71, and is disposed immediately beneath a funnel-like structure 72 which serves to direct into the pan the stream of water discharged from the discharge orifice 24. As a practical matter, the funnel-like structure 72 is provided with an inclined cover screen 74 over which a delivery of ice is effected as the ice is discharged from the orifice 24 and deposited in an ice repository 76.

As best shown in FIG. 2, within the manifold housing 66 there is defined a manifold chamber 80. The manifold chamber 80 is of a diameter substantially equal to the diameter of the outlet orifice 70 and is provided with a metering orifice 82 through which a flow of water is discharged at a constant rate. Moreover, communication between the holding tank 52 and the manifold chamber 80 is established through a delivery orifice 84 provided in the manifold housing 66 in coaxial alignment with the orifice 70. Preferably, the metering orifice 82 and the delivery orifice 84 are of a common diameter, substantially less than the diameter of the outlet orifice 70 for the receiver pan 68. Consequently, once a head is established for the body of water 71, water is fed to the holding tank 52 via the conduit 64 for thus establishing a head for the body of water 60. Thus, as the level of the body of water 71 increases, the level of the body of water 60 similarly increases. Conversely, as the level of the body of water 71 decreases, the level of the body of water 60 is caused to decrease.

The significance of a delivery of water to and a discharge of water from the holding tank 52 should be appreciated. lt is important to recall that during the initial phase of a cycle of operation for the ice-making machine 10, the flow rate for the stream of water delivered from the discharge orifice 24 is greatest and, consequently, is relatively warm. Thus the level of the body of water 71 is elevated quite rapidly, even though water is being discharged from the manifold chamber via the metering orifice 82 and the delivery orifice 84. Similarly, the level of the body of water 60 rapidly is increased. Moreover, during this phase of an operational cycle, the temperature of the bodies of water 71 and 60 is at its greatest value.

However, during later phases of the cycle of operation of the machine 10, just prior to an initiation of an ice-harvesting operation, the flow rate of the stream of water from the discharge orifice 24 is substantially reduced, and the temperature of the water is substantially reduced, due to the temperature exchange occurring within the evaporator section 14. Hence, as the level of the bodies of Water begins to fall the temperature of the stream has already begun to fall. Of course, as the level of the body of water 71 declines, the level of the body of water 60 experiences a similar decline with the relatively warm water, previously delivered to the holding tank 52, being returned to the manifold chamber 80, via the conduit 64. The result is that the temperature of the water within the manifold chamber is increased so that the metering orifice remains free from deposits of ice. Thus the rate of discharge through the metering orifice 82 remains substantially constant throughout each cycle of operation. Thus, icing of the control unit 12 is precluded.

As a practical matter, in order to avoid introduction into the manifold chamber 80 pieces of ice or chips which may find their way into the receiver pan 68, a retainer wire 85 may be welded in diametric relation across the orifice 70, where so desired.

Disposed immediately beneath the orifice 82, in receiving relation therewith, there is a delivery pan 86. This pan is connected with the input side of the pump 20 via a delivery line 88. Thus the water discharged from the metering orifice 82 ultimately returns to the input side of the pump 20 for recirculation through the evaporator section 14 of the machine 10.

OPERATION It is believed that in view of the foregoing description, the operation of the device will readily be understood and it will be briefly reviewed at this point.

With the control unit 12 coupled with the ice-making machine 10, in the manner hereinbefore described, the control unit 12 is employable for imposing cyclic control over the operation of the ice-making machine.

Assuming, that the pump 20 is operating to supply a continuous stream of water to the ice-making tube 16, via the feeder line 22, a continuous stream of water is established through the evaporator section 14. This stream is, of course, discharged from the discharge end of the tube 16, at the port 24, and is received in the receiver pan 68. Assuming further, that the selector valve 34 is in its first position, so that a flow of gaseous refrigerant is established through the temperature control jacket formed by the outer tube 18 about the icemaking tube 16, a chilling of the wall of the ice-making tube 16 is occurring. As chilling of the water flowing through the ice-making tube 16 occurs, the thickness of a collection of ice thus formed and deposited on the inner surface of the wall of the tube 16 is substantially increased. As anattendant result, the flow rate for the water discharged from the discharge orifice 24 is decreased, whereupon the level of the body of water 71, within the receiver pan 68, and the body of water 60 confined within the holding tank 52, begins to drop, as water is discharged from the manifold chamber 80 via the metering orifice 82.

It is to be understood that the temperature of the water discharged from the discharge orifice 24 is substantially lower than the temperature of the body 60 confined within the holding tank 52. However, as the water from the receiver pan 68 is co-mingled with the water returned from the holding tank 52, within the manifold chamber 80, a collection of ice and slush within the manifold chamber is substantially eliminated. Thus, the metering orifice 82 is permitted to discharge water at a constant rate for continuing to lower the level of the bodies 71 and 60.

Of course, the elevation of the buoyant mass 48 is lowered as the level of the body 60 is lowered. As the buoyant mass 48 moves downwardly. through a predetermined distance, the arm 50 causes the float switch 44 to achieve a circuit-closed condition for completing an electrical circuit between the source of electrical potential, not shown. and the solenoid 42. Thus, an electrical signal is applied to the solenoid 42 for causing the solenoid to responsively reposition the selector valve 34 to its second position.

In its second position. the valve 34 causes the discharge side of the compressor section 30 to communi cate with the by-pass line 40 whereby compressed refrigerant in its heated condition is caused to by-pass the condensor-reservoir section 26 and be delivered to the temperature control jacket defined by the outer tube 18 about the ice-making tube 16. The heated gas serves to heat the wall of the ice-making tube 16 for causing the collection of ice adhered thereto to be released. Due to the back pressure now established within the feeder line 22, the released deposits of ice are ejected from the evaporator section 14, via the discharge orifice 24.

Of course, once the ice has been forced from the tube 16. the flow rate of water through the ice-making tube is rapidly increased, whereupon the level of the bodies of water 71 and 60 is rapidly increased for thus causing the mass 48 to be elevated for thereby causing the switch element of the float switch 44 to open the previously established electrical circuit between the source of electrical potential and the solenoid 42. ln response to an opening of the circuit, the spring-load of the solenoid 42 causes the selector valve 34 to switch to its first position whereupon the ice-harvesting phase of the machines cycle of operation is completed and the iceforming phase of the cycle is initiated.

It should readily be apparent that through the instant invention there has been provided a practical solution to the perplexing problem of providing an economic and efficient control unit for ice-making machines.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Having described my invention, what I claim as new and desire to secure by Letters Patent is: v

1. An improved harvest control unit in combination with an ice-making machine of the type including an ice making tube, means for delivering a continuous flow of water through said tube at a variable rate. and a hot-gas circuit including means responsive to an electrical harvesting signal for initiating ice-harvesting operations, comprising:

A. a receiver pan for receiving water delivered through said tube;

B. a holding tank disposed in spaced relation with said receiver pan for confining a relatively warm body of water having a variable level;

C. a float switch connected with said holding tank for providing an electrical harvesting signal in response to a predetermined variation in the level of said body;

D. a manifold chamber connected in free-flow communication with the lower portions of said receiver pan and said holding tank; and

E. means defining in said manifold a metering orifice for discharging from the chamber. at a substantially fixed rate, water delivered thereto from said pan and from said holding tank.

2. The harvest control unit of claim 1 wherein said manifold chamber and said receiver pan are connected in communication through an orifice of a predetermined diameter substantially larger than the diameter of said metering orifice.

3. The harvest control unit of claim 2 wherein the manifold chamber is connected in communication with the lower portion of said holding tank throtigh an orifice having a diameter substantially equal to the diameter of the metering orifice.

4. The harvest control unit of claim 3 wherein said float switch includes a buoyant mass supported by said body of water and means for closing an electrical circuit in response to a lowering of said mass relative to the bottom portion of the holding tank.

5. The control unit of claim 4 further including means for vertically adjusting said float switch relative to said tank.

6. In an ice-making machine of the type including an ice-making tube confined within tubular means defining a concentrically related temperature control jacket; a water delivery circuit connected with said tube and having a pump for forcing a continuous stream of water through the tube; and a gas delivery circuit connected with said jacket and having refrigerant means connectable with the jacket for delivering a flow of refrigerant gas therethrough for chilling the wall of said tube sufficiently for causing a collection of ice to adhere to the wall, and further having harvesting means connectable with the jacket for delivering a flow of heated gas therethrough for heating said wall sufficiently for initiating a release of the ice from said wall, and selectively operable valve means connected with the refrigerant means, the harvesting means and the jacket for alternately connecting said refrigerant means and said harvesting means with said jacket, the improvement comprising:

A. electrically responsive valve-actuating means connected with said valve means for selectively initiating an operation thereof; B. switch means connected with said valve-actuating means for delivering electrical signals thereto; and C. switch-actuating means for actuating said switch means including a holding-tank for receiving and confining a body of relatively warm water having a variable level, a float supported by said body of water and connected with said switch means for actuating the switch means in response to changes in the level of the body. means for varying the level of said body of water including a receiver pan supported in spaced relation with said holding tank and disposed beneath the discharge end of said tube for receiving the stream of water as it is forced through said tube. means defining an outlet orifice adjacent to the bottom portion of said receiver pan means defining a manifold chamber connected with said outlet orifice for receiving the water from said receiver pan. means defining within the chamber a metering orifice for discharging water from said chamber at a preselected. substantially constant rate. means defining within the chamber a delivery orifice. means defining within the bottom said pump. portion of the holding tank an inlet orifice. a free- 7. The improvement of claim 6 further comprising a flow tubular conduit extending between the deli\'- wire extended diametrically across said outlet orifice ery orifice of the manifold chamber and the inlet for restraining from entry to said manifold chamber ice orifice of the holding tank, and means for deliversuspended in the water received thereby. ing water discharged from said metering orifice to 

1. An improved harvest control unit in combination with an icemaking machine of the type including an ice-making tube, means for delivering a continuous flow of water through said tube at a variable rate, and a hot-gas circuit including means responsive to an electrical harvesting signal for initiating ice-harvesting operations, comprising: A. a receiver pan for receiving water delivered through said tube; B. a holding tank disposed in spaced relation with said receiver pan for confining a relatively warm body of water having a variable level; C. a float switch connected with said holding tank for providing an electrical harvesting signal in response to a predetermined variation in the level of said body; D. a manifold chamber connected in free-flow communication with the lower portions of said receiver pan and said holding tank; and E. means defining in said manifold a metering orifice for discharging from the chamber, at a substantially fixed rate, water delivered thereto from said pan and from said holding tank.
 2. The harvest control unit of claim 1 wherein said manifold chamber and said receiver pan are connected in communication through an orifice of a predetermined diameter substantially larger than the diameter of said metering orifice.
 3. The harvest control unit of claim 2 wherein the manifold chamber is connected in communication with the lower portion of said holding tank through an orifice having a diameter substantially equal to the diameter of the metering orifice.
 4. The harvest control unit of claim 3 wherein said float switch includes a buoyant mass supported by said body of water and means for closing an electrical circuit in response to a lowering of said mass relative to the bottom portion of the holding tank.
 5. The control unit of claim 4 further including means for vertically adjusting said float switch relative to said tank.
 6. In an ice-making machine of the type including an ice-making tube confined within tubular means defining a concentrically related temperature control jacket; a water delivery circuit connected with said tube and having a pump for forcing a continuous stream of water through the tube; and a gas delivery circuit connected with said jacket and having refrigerant means connectable with the jacket for delivering a flow of refrigerant gas therethrough for chilling the wall of said tube sufficiently for causing a collection of ice to adhere to the wall, and further having harvesting means connectable with the jacket for delivering a flow of heated gas therethrough for heating said wall sufficiently for initiating a release of the ice from said wall, and selectively operable valve means connected with the refrigerant means, the harvesting means and the jacket for alternately connecting said refrigerant means and said harvesting means with said jacket, the improvement comprising: A. electrically responsive valve-actuating means connected with said valve means for selectively initiating an operation thereof; B. switch means connected with said valve-actuating means for delivering electrical signals thereto; and C. switch-actuating means for actuating said switch means including a holding-tank for receiving and confining a body of relatively warm water having a variable level, a float supported by said body of wAter and connected with said switch means for actuating the switch means in response to changes in the level of the body, means for varying the level of said body of water including a receiver pan supported in spaced relation with said holding tank and disposed beneath the discharge end of said tube for receiving the stream of water as it is forced through said tube, means defining an outlet orifice adjacent to the bottom portion of said receiver pan, means defining a manifold chamber connected with said outlet orifice for receiving the water from said receiver pan, means defining within the chamber a metering orifice for discharging water from said chamber at a preselected, substantially constant rate, means defining within the chamber a delivery orifice, means defining within the bottom portion of the holding tank an inlet orifice, a free-flow tubular conduit extending between the delivery orifice of the manifold chamber and the inlet orifice of the holding tank, and means for delivering water discharged from said metering orifice to said pump.
 7. The improvement of claim 6 further comprising a wire extended diametrically across said outlet orifice for restraining from entry to said manifold chamber ice suspended in the water received thereby. 